A leveling device is an optical instrument used to verify points in the same horizontal plane, and can be used to measure true horizontal or relative heights. Leveling devices vary in size, shape, and use. One type of leveling device is a spirit level or bubble level, which includes an enclosed tubular or circular chamber containing an air pocket housed within a liquid (e.g., spirit vial). Leveling devices can be used to indicate and/or measure “cant”, which is defined as a tilt or a slope to one slope relative to a vertical axis of the earth and/or a surface of the earth.
In a long-range shooting, many factors that might not affect a short-range shooting have a large impact on the ability to hit a target with dead-on accuracy. One factor includes “cant”, or the tilting of a projectile launcher (e.g., a firearm such as a rifle, a shotgun, a pistol, or the like; an explosive launcher such as a grenade launcher, rocket-propelled grenade launcher, or the like; a bow; or the like) to one side relative to the vertical axis of the earth. Long-range shooters have long used scopes with levels to eliminate canting with projectile launchers. The level is generally mounted either on the projectile launcher (e.g., on top of the projectile launcher) or on the projectile launcher scope (e.g., on top of the scope tube, side of the scope tube). When aiming at the target with the projectile launcher scope, the long-range shooters need to make sure that the level on the projectile launcher or the projectile launcher scope is leveled by looking at the level and that the target is on the aiming point through an eyepiece of the projectile launcher scope at the same time. However, one-eyed shooters can focus on one or the other and even two-eyed shooters may have difficult time in paying the same degree of attentions to both the level and the eyepiece of the scope projectile launcher. As a result, this creates a subtle canting which results in a significant deviation from the planned impact point. In general, 6 degrees of a canting in 1,000-yard (e.g., 914 m) long-range shooting creates up to 3 feet (e.g., 91.4 cm) deviation from the target, which can result in missing the target.
In construction, a construction level (e.g., carpenter's level or contractor's level) may be placed on a surface to determine whether the surface is level (e.g., relative to horizontal) or plumb (e.g., relative to vertical). For example, a level may be set on, hung on, and/or held against a surface (e.g., shelf, seat, tabletop, countertop, furnituretop, wall, house frame member, roof frame member, metal surface, concrete surface, tiled surface, wooden surface, drywall surface, or the like) to eliminate canting relative to the vertical axis of the earth and/or the surface of the earth.
Therefore, it would be desirable to provide an apparatus that cures the deficiencies of prior approaches.